Psychopharmacology Flashcards
what is psychopharmacology?
the interaction between psychoactive drugs and the body
what are psychoactive drugs able to do?
- alter neurotransmission
- affect mood or behaviour
- be effective in managing psychological problems
what can psychopharmacology explain?
how the brain works and the causes of different psychiatric disorders, in order to lead to better treatments
what is psychopharmacology helpful for?
dealing with problematic drug use, such as the concerns with health consequences and the controversy of drug use to aid psychiatric disorders
what is pharmacokinetics?
the study of how drugs are handled in the body
routes of administration
oral
rectal
intravenous
transdermal
inhalation
sublingual
benefits of oral admission
- convenient
- cheapest route
- easy to use
- safe and acceptable
limitations of oral admission
- less amount of drug reaches target tissue
- slow absorption must take place
- not preferred in emergency situations
- unpredictable amount
- might cause gastric irritation
benefits of rectal admission
- avoids nausea
- one of the only options if the patient is unconscious
- drug cannot be destroyed by enzymes in the body
limitations of rectal admission
- reduced surface area can limit absorption
- can cause irritation
- patients may refuse to take them
benefits of intravenous admission
- quick and precise effect
- preferred method for unconscious patients
- can control the amount of drug in blood circulation
- preferred for emergencies as the drug reaches blood stream immediately
limitations of intravenous admission
- requires skill to inject
- greater risk of injection
- risk of blood clots
- expensive
- can be painful or lead to inflammation
benefits of transdermal admission
- pain-free self-administration
- releases drugs into blood plasma at a slow and steady rate
- ease of use
- less frequent drug use
limitations of transdermal admission
- potential for allergic reaction to patch or adhesives
- tough barrier of skin
- unsuitable in emergency situations
- drug must be potent or else patches would be too large
benefits of inhalation admission
- fewer doses required
- can be used for unconscious patients
- local delivery to target area
- beneficial for asthmatic patients
- drug takes effect quickly via absorption
limitations of inhalation admission
- can lead to further breathing issues
- special apparatus required
- may irritate lungs with prolonged use
- expensive
benefits of sublingual admission
- dissolved easily
- spitting out the drug removes its effect
- drug enters the blood quickly through rapid absorption
- avoids drug disruption
- easy to monitor amount taken
- used during emergencies for a fast effect
limitations of sublingual admission
- drug may be accidentally swallowed
- inconvenient
- eating can inhibit absorption
how are drugs able to gain access to blood plasma?
by crossing cell membranes
what can the diffusion of drugs across the lipid membrane be affected by?
- lipid-soluble and small molecules diffuse best
- un-ionised drug molecules are more lipid-soluble
by circulating through the blood plasma, what are drugs able to gain access to?
tissue sites
what do drugs encounter at these tissue sites?
receptors that they have an affinity to
they bind to these receptors, which brings about the pharmacological response
what is the target site for psychoactive drugs?
typically the brain
how do side effects of psychoactive drugs occur?
the plasma is still able to reach other parts of the body, as receptors bind outside of the target site
how are some drugs inactivated once distributed in the body?
how does this prevent them from accessing target sites?
- being stored in fat
- being attached to blood plasma proteins
because they are unable to enter the brain
how can drug molecules be prevented from entering the brain?
brain capillaries are surrounded by a dense wall structure of glial cells
this means that even lipid-soluble molecules cannot easily cross the blood brain barrier
where does the process of metabolism mainly occur?
in the liver, where there are enzymes that are important in aiding drug transformation
why does metabolism take place?
drugs which cannot be eliminated must undergo the process of transformation, as it is essential for drugs to be removed from the body
different routes of elimination
urine via the kidneys (only possible for water-soluble compounds, meaning that fat-soluble drugs must undergo metabolism)
via the lungs
via sweat and hair
agonist drugs
enhance the effects of a neurotransmitter
antagonist drugs
block the effects of a neurotransmitter by binding to a receptor
direct agonist
mimic the effects of a particular neurotransmitter by binding to the same postsynaptic receptors and producing a similar response
indirect agonist
enhances the action of a neurotransmitter by releasing the drug into the synaptic cleft or blocking reuptake
full agonist
fully reproduce the effect of the endogenous neurotransmitter
partial agonist
will not achieve the full maximal effect of the neurotransmitter
direct antagonist
prevent neurotransmitters from binding to the same site on the receptor
‘receptor blocker’
indirect antagonist
inhibit the release of neurotransmitters
inverse agonist
binds to a receptor and brings about an effect, but this effect is the opposite
what does the magnitude of a drug-receptor effect depend on?
- concentration at the target site
- the affinity of the drug for the receptor site
how can drug efficacy and potency be quantified by?
a dose-resonse curve
what does plotting the dose-response curve allow?
plotting the relationship between drug dose and response allows comparison of the pharmacological profile of drugs
drug efficacy
a measure to the extent to which a drug stimulates its target receptors
potency
the amount of drug required to produce a specific effect
ED50
is the dose producing half the maximal effect
(a measure of potency)
efficacious dose
allosteric modulation
a chemical (modulator) binds to a different part of the receptor than the neurotransmitter, and alters the receptor’s response by changing the shape
what is the therapeutic index?
gives a measure of the relative safety of a drug, by comparing the difference between the therapeutic effect and the toxic effect
therapeutic index
LD50/ED50
100 is high and a wide separation between the two is desired
LD50
lethal dose
half-life
the time required for a quantity to reduce to half of its initial value
what does a longer half-life mean?
the drug sticks around longer
